An Assessment of PCBs and OC Pesticides in Eggs of Double-crested (Phalacrocorax auritus) and Pelagic (P. pelagicus) Cormorants from the West Coast of Canada, 1970 to 2002

Abstract

Eggs of double-crested and pelagic cormorants were collected between 1970 and 2002 from colonies in the Strait of Georgia, BC, Canada, and assayed for concentrations of organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs). Double-crested cormorant eggs from the early 1970's contained up to 4.1 mg kg-1 p,p'-DDE and 12.5 mg kg-1 sigmaPCBs. Corresponding values for pelagic cormorant eggs were 1.5 mg kg-1 p,p'-DDE and 3.9 mg kg-1 sigmaPCBs. Egg tissue concentrations of the dominant OC pesticides and sigmaPCBs dropped mainly during the 1970's, with minor declines thereafter. The data suggest that contaminant levels in cormorants have now stabilized at low levels throughout the resident population. Small but significant latitudinal gradients in several OC pesticides and PCBs indicated that areas of the southern strait were more contaminated than areas of the less populated northern strait. Interspecific differences in contamination may indicate that pelagic cormorants have a reduced capacity to metabolize chlordanes, DDT and PCBs compared to double-crested cormorants. Alternatively, the two species may have more divergent prey bases than previously thought. During the 1980's, TCDD toxic equivalents, largely contributed by polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), were correlated with physiological and biochemical alterations. Also, from 1989 to 1990, four deformed cormorant chicks (two of each species) were found during nest visits; none were found between 1991 and 1995. The relative rates of deformed chicks were 6 per 10,000 for double-crested and 16 per 10,000 for pelagic cormorants. The findings of deformed chicks were coincident with the period of highest PCDD and PCDF contamination; however, the sample sizes were too low to derive a substantive connection. Colony-wide productivity of double-crested cormorants was poorer in the southern colonies where PCBs in particular were elevated. While of concern, these lines of evidence are insufficient to conclude that chlorinated hydrocarbon contamination was a dominant contributor to population declines. It seems more probable that ecological variables, particularly changing prey and predator dynamics, drove the reductions in population size.

Evaluation of pesticide contamination in Dilek National Park, Turkey

“…The pesticides in the water and sorbed to sediments can be consumed directly or after they have been accumulated in plant matter (Celik et al 2006;Gjershaug et al 2008;Kim et al 2008b). Research has shown that birds that ingested organochlorines exhibited abnormal reproductive behavior, thinning of shells, feminization of males, and immunotoxicologic responses (Cid et al 2007;Harris et al 2005). The lesser kestrel population in Israel exhibited a dramatic decline as a result of ingesting crickets sprayed with pesticides (Liven-Schulman et al 2004).…”

Integrated Mercury Monitoring Program for Temperate Estuarine and Marine Ecosystems on the North American Atlantic Coast

“…They include the National Atmospheric Deposition Program’s Mercury Deposition Network for air (Lamb and Bowersox 2000), the National Oceanographic and Atmospheric Administration’s (NOAA) Mussel Watch Program for shellfish (Chase et al 2001), the U.S. Environmental Protection Agency’s (USEPA) National Coastal Assessment Program for shellfish and marine fish (Cunningham et al 2003), the U.S. Geological Survey’s Contaminant Exposure and Effects – Terrestrial Vertebrates program for terrestrial wildlife (Cohen et al 2003), and the Atlantic, Arctic and Pacific Seabird Egg Contaminant Monitoring Programs of Environment Canada (Pearce et al, 1979; Harris et al, 2005; Braune, 2007). We use these existing programs as a basis for identifying indicators and recommending Hg monitoring locations.…”

“…Environmental Protection Agency National Coastal Assessment Program (Cunningham et al, 2003) 3 Environment Canada Seabird Egg Contaminant Monitoring Program (Harris et al, 2005; Braune, 2007) …”

Peregrine Falcons Enable Two Species of Colonial Seabirds to Breed Successfully by Excluding Other Aerial Predators

“…Over time, the aerial predators can drive local murre colonies into decline (Parrish et al 2001). An increasing population of Bald Eagles is also thought to underlie declines in Pelagic Cormorant (Phalocrocorax pelagicus) populations across western North America (Carter et al 2009;Chatwin et al 2002;Harris et al 2005).…”